The present invention relates to methods for regulating gastrointestinal motility. More particularly, the invention relates to the use of amylin and agonists of amylin in the treatment of disorders which would be benefited with agents useful in delaying and/or slowing gastric emptying. The invention also relates to the use of amylin antagonists to accelerate gastric emptying, for example, in treating gastric hypomotility and associated disorders.
Amylin is a 37-amino acid protein hormone. It was isolated, purified and chemically characterized as the major component of amyloid deposits in the islets of pancreases of human Type 2 diabetics (Cooper et al., Proc. Natl. Acad. Sci., USA, 84:8628-8632 (1987)). The amylin molecule has two important post-translational modifications: the C-terminus is amidated, and the cysteines in positions 2 and 7 are cross-linked to form an N-terminal loop. The sequence of the open reading frame of the human amylin gene shows the presence of the Lys-Arg dibasic amino acid proteolytic cleavage signal, prior to the N-terminal codon for Lys, and the Gly prior to the Lys-Arg proteolytic signal at the CLAIMS-terminal position, a typical sequence for amidation by protein amidating enzyme, PAM (Cooper et al., Biochem. Biophys. Acta, 1014:247-258 (1989)). Amylin is the subject of United Kingdom patent application Serial No. 8709871, filed Apr. 27, 1987, and corresponding U.S. applications filed Apr. 27, 1988, Nov. 23, 1988 and May 2, 1989.
In Type 1 diabetes, amylin has been shown to be deficient and combined replacement with insulin has been proposed as a preferred treatment over insulin alone, for instance in limiting hypoglycemic episodes. The use of amylin for the treatment of diabetes mellitus is the subject of United Kingdom patent application Serial No. 8720115 filed on Aug. 26, 1987, by G. J. S. Cooper, and filed as patent application Ser. No. 236,985 in the United States on Aug. 26, 1988. Pharmaceutical compositions containing amylin and amylin plus insulin are described in U.S. Pat. No. 5,124,314, issued Jun. 23, 1992.
Excess amylin action mimics key features of Type 2 diabetes and amylin blockade has been proposed as a novel therapeutic strategy. It has been disclosed in commonly-owned copending U.S. patent application Ser. No. 275,475, filed Nov. 23, 1988 by Cooper, G. J. S. et al., the contents of which are incorporated herein by reference, that amylin causes reduction in both basal and insulin-stimulated incorporation of labelled glucose into glycogen in skeletal muscle. The latter effect was also disclosed to be shared by CGRP (see also Leighton, B. and Cooper, G. J. S., Nature, 335:632-635 (1988)). Amylin and CGRP were approximately equipotent, showing marked activity at 1 to 10 nM. Amylin is also reported to reduce insulin-stimulated uptake of glucose into skeletal muscle and reduce glycogen content (Young et al., Amer. J. Physiol. 259:457-46-1 (1990)). The treatment of Type 2 diabetes and insulin resistance with amylin antagonists is disclosed.
Both the chemical structure and the gene sequence of amylin have been said to support the determination that it is a biologically active or xe2x80x9cmessengerxe2x80x9d molecule. The chemical structure is nearly 50% identical to the calcitonin-gene-related peptides (CGRP), also 37 amino acid proteins which are widespread neurotransmitters with many potent-biological actions, including vasodilation. Amylin and CGRP share the 2Cys-7Cys disulphide bridge and,the C-terminal amide, both of which are essential for full biologic activity (Cooper et al. Proc. Natl. Acad. Sci., 85-7763-7766 (1988)).
Amylin may be one member of a family of related peptides which include CGRP, insulin, insulin-like growth factors, and the relaxins and which share common genetic heritage (Cooper, G. J. S., et al., Prog. Growth Factor Research 1:99-105 (1989)). The two peptides calcitonin and CGRP-1 share common parentage in the calcitonin gene where alternative processing of the primary mRNA transcript leads to the generation of the two distinct peptides, which share only limited sequence homology (about 30%) (Amara, S. G. et al., Science, 229:1094-1097 (1985)). The amylin gene sequence is typical for a secreted messenger protein, with the MRNA coding a prepropeptide with processing sites for production of the secreted protein within the Golgi or secretary granules. Amylin is mainly co-localized with insulin in beta cell granules and may share the proteolytic processing enzymes that generate insulin from pro-insulin.
Amylin is primarily synthesized in pancreatic beta cells and is secreted in response to nutrient stimuli such as glucose and arginine. Studies with cloned beta-cell tumor lines (Moore et al., Biochem. Biophys. Res. Commun., 179(1) (1991)), isolated islets (Kanatsuka et al., FEBS Lett., 259(1), 199-201 (1989)) and perfused rat pancreases (Ogawa et al., J. Clin. Invest., 85:973-976 (1990)) have shown that short pulses, 10 to 20 minutes, of nutrient secretagogues such as glucose and arginine, stimulate release of amylin as well as insulin. The molar amylin:insulin ratio of the secreted proteins varies between preparations from about 0.01 to 0.4, but appears not to vary much with different stimuli in any one preparation. However, during prolonged stimulation by elevated glucose, the amylin:insulin ratio can progressively increase (Gedulin et al., Biochem. Biophys. Res. Commun., 180(1):782-789 (1991)). Thus, perhaps because gene expression and rate of translation are independently controlled, amylin and insulin are not always secreted in a constant ratio.
Amylin-like immunoreactivity has been measured in circulating blood in rodents and humans by a variety of radioimmunoassays all of which use rabbit anti-amylin antiserum, and most of which use an extraction and concentration procedure to increase assay sensitivity. In normal humans, fasting amylin levels from 1 to 10 pM and post-prandial or post-glucose levels of 5 to 20 pM have been reported (e.g., Hartter et al., Diabetologia, 34:52-54 (1991)); Sanke et al., Diabetolopia, 34:129-132 (1991)); Koda et al., The Lancet, 339:1179-1180 (1992)). In obese, insulin-resistant individuals, post-food amylin levels can go higher, reaching up to about 50 pM. For comparison, the values for fasting and post-prandial insulin are 20 to 50 pM, and 100 to 300 pM respectively in healthy people, with perhaps 3-to 4-fold higher levels in insulin-resistant people. In Type 1 diabetes, where beta-cells are destroyed, amylin levels are at or below the levels of detection and do not rise in response to glucose (Koda et al., The Lancet, 339, 1179-1180 (1992)). In normal mice and rats, basal amylin levels have been reported from 30 to 100 pM, while values up to 600 pM have been measured in certain insulin-resistant, diabetic strains of rodents (e.g., Huang et al., Hypertension, 19:I-101-I-109 (1992); Gill et al., Life Sciences, 48:703-710 (1991)).
It has been discovered that certain actions of amylin are similar to known non-metabolic actions of CGRP and calcitonin; however, the metabolic actions of amylin discovered during investigations of this newly identified protein appear to reflect its primary biologic role. At least some of these metabolic actions are mimicked by CGRP, albeit at doses which are markedly vasodilatory (see, e.g., Leighton et al., Nature, 335:632-635 (1988); Molina et al., Diabetes, 39:260-265 (1990)).
The first discovered action of amylin was the reduction of insulin-stimulated incorporation of glucose into glycogen in rat skeletal muscle (Leighton et al., Nature, 335:632-635 (1988)); the muscle was made xe2x80x9cinsulin-resistantxe2x80x9d. Subsequent work with rat soleus muscle ex-vivo and in vitro has indicated that amylin reduces glycogen-synthase activity, promotes conversion of glycogen phosphorylase from the inactive b form to the active a form, promotes net loss of glycogen (in the presence or absence of insulin), increases glucose-6-phosphate levels, and can increase lactate output (see, e.g., Deems et al., Biochem. Biophys. Res. Commun., 181(1):116-120 (1991)); Young et al., FEBS Letts, 281(1,2):149-151 (1991)). Whether amylin interferes with glucose transport per se is uncertain (see e.g. Young et al., Am. J. Physiol., 259:E457-E461 (1990); Zierath et al., Diabetologia, 35:26-31 (1992)). Studies of amylin and insulin dose-response relations show that amylin acts as a noncompetitive or functional antagonist of insulin in skeletal muscle (Young et al., Am. J. Physiol., Am. J. Physiol., 263(2):E274-E281 (1992)). There is no evidence that amylin interferes with insulin binding to its receptors, or the subsequent activation of insulin receptor tyrosine kinase (Follett et al., Clinical Research 39(1):39A (1991); Koopmans et al., Diabetolopia, 34, 218-224 (1991)). The actions of amylin on skeletal muscle resemble those of adrenalin (epinephrine). However, while adrenalin""s actions are believed to be mediated largely by cAMP, some workers have concluded that amylin""s actions are not mediated by cAMP (see Deems et al., Biochem. Biophys. Res. Commun., 181(1):116-120 (1991)), while still others report that amylin does activate adenyl cyclase and increases cAMP in skeletal muscle (Moore and Rink, Diabetes 42:5,821 June (1993)), consistent with transduction of its effect on glycogen metabolism via cAMP-dependent protein kinase phosphorylation of synthase and phosphorylase.
It is believed that amylin acts through receptors present in plasma membranes. It has been reported that amylin works in skeletal muscle via a receptor-mediated mechanism that promotes glycogenolysis, by activating the rate-limiting enzyme for glycogen breakdown, phosphorylase a (Young, A. et al., FEBS Letts., 281:149-151 (1991)). Studies of amylin and CGRP, and the effect of the antagonist 8-37CGRP, suggest that amylin acts via its own receptor (Wang et al., FEBS Letts., 219:195-198 (1991 b)), counter to the conclusion of other workers that amylin may act primarily at CGRP receptors (e.g., Chantry et al., Biochem. J., 277:139-143 (1991); Galeazza et al., Peptides, 12:585-591 (1991); Zhu et al., Biochem. Biophys. Res. Commun., 177(2):771776 (1991)). Recently, amylin receptors and their use in various methods for screening and assaying for amylin agonist and antagonist compounds were described in International Application Number PCT/US92/02125, published Oct. 1, 1992, and titled xe2x80x9cReceptor-Based Screening Methods for Amylin Agonists and Antagonists.xe2x80x9d
While amylin has marked effects on hepatic fuel metabolism in vivo, there is no general agreement as to what amylin actions are seen in isolated hepatocytes or perfused liver. The available data do not support the idea that amylin promotes hepatic glycogenolysis, i.e., it does not act like glucagon (e.g., Stephens, et al., Diabetes, 40:395-400 (1991)); Gomez-Foix et al., Biochem J., 276:607-610 (1991)). It has been suggested that amylin may act on the liver to promote conversion of lactate to glycogen and to enhance the amount of glucose able to be liberated by glucagon (see Roden et al., Diabetologia, 35:116-120 (1992)). Thus, amylin could act as an anabolic partner to insulin in liver, in contrast to its catabolic action in muscle.
The effect of amylin on regional hemodynamic actions, including renal blood flow, in conscious rats was recently reported (Gardiner et al., Diabetes, 40:948-951 (1991)). The authors noted that infusion of rat amylin was associated with greater renal vasodilation and less mesenteric vasoconstriction than is seen with infusion of human xcex1-CGRP. They concluded that, by promoting renal hyperemia to a greater extent than did xcex1-CGRP, rat amylin could cause less marked stimulation of the renin-angiotensin system, and thus, less secondary angiotensin II-mediated vasoconstriction. It was also noted, however, that during coninfusion of human xcex1-8-37CGRP and rat amylin renal and mesenteric vasoconstrictions were unmasked, presumably due to unopposed vasoconstrictor effects of angiotensin II, and that this finding is similar to that seen during coinfusion of human A-CGRP and human xcex1-8-37CGRP (id. at 951).
In fat cells, contrary to its adrenalin-like action in muscle, amylin has no detectable actions on insulin-stimulated glucose uptake, incorporation of glucose into triglyceride, CO2 production (Cooper et al., Proc. Natl. Acad. Sci., 85:7763-7766 (1988)) epinephrine-stimulated lipolysis, or insulin-inhibition of lipolysis (Lupien J. R., and Young, A. A., xe2x80x9cDiabetes Nutrition and metabolismxe2x80x94Clinical and Experimentalxe2x80x9d, Vol. 6(1), pages 13-18 (February 1993)). Amylin thus exerts tissue-specific effects, with direct action on skeletal muscle, marked indirect (via supply of substrate) and perhaps direct effects on liver, while adipocytes appear xe2x80x9cblindxe2x80x9d to the presence or absence of amylin. No direct effects of amylin on kidney tissue have been reported.
It has also been reported that amylin can have marked effects on secretion of insulin. In isolated islets (Ohsawa et al., Biochem. Biophys. Res. Commun., 160(2):961-967 (1989)), in the perfused pancreas (Silvestre et al., Reg. Pept., 31-23-31 (1990), and in the intact rat (Young et al., Mol. Cell. Endocrinol., 84:R1-R5 (1992)), some experiments indicate that amylin down-regulates insulin secretion. The perfused pancreas experiments point to selective down-regulation of the secretary response to glucose with sparing of the response to arginine. Other workers, however, have been unable to detect effects of amylin on isolated xcex2-cells, on isolated islets, or in the whole animal (see Broderick et al., Biochem. Biophys. Res. Comm., Vol. 177:932-938 (1991) and references therein).
The most striking effect of amylin in vivo is stimulation of a sharp rise in plasma lactate, followed by a rise in plasma glucose (Young et al., FEBS Letts, 281(1,2):149-151 (1991)). Evidence indicates that the increased lactate provides substrate for glucose production and that amylin actions can occur independent of changes in insulin or glucagon. In xe2x80x9cglucose clampxe2x80x9d experiments, amylin infusions cause xe2x80x9cinsulin resistance,xe2x80x9d both by reducing peripheral glucose disposal, and by limiting insulin-mediated suppression of hepatic glucose output (e.g., Frontoni et al., Diabetes, 40:568-573 (1991); Koopmans et al., Diabetologia, 34, 218-224 (1991)).
In lightly anesthetized rats which were fasted for 18 hours to deplete their stores of hepatic glycogen, amylin injections stimulated rises in plasma lactate from about 0.5 to 1.5 mM followed by a prolonged increase in plasma glucose levels from about 6 to 11 mM. These effects were observed for both intravenous and subcutaneous injections (Young et al., FEBS Letts., 281(1,2):149-151 (1991)). The effects of amylin in fed animals differ quantitatively from its effects in fasted animals. In fed rats, with presumably normal liver glycogen stores, amylin causes a more pronounced and prolonged rise in plasma lactate; however, there is only a modest rise in plasma glucose. It has been suggested that amylin promotes the xe2x80x9creturn limbxe2x80x9d of the Cori cycle, i.e., muscle glycogen via breakdown to lactate provides substrate for hepatic gluconeogenesis and glycogen production and probably triglyceride synthesis. Insulin drives the forward limb, i.e., uptake of glucose into muscle and production of muscle glycogen. Insulin and amylin can thus be seen as partners in regulating the xe2x80x9cindirectxe2x80x9d pathway of post-prandial hepatic glycogen repletion. xe2x80x9cInsulin resistancexe2x80x9d in muscle and liver may be under normal, physiologic regulation by amylin.
Non-metabolic actions of amylin include vasodilator effects which may be mediated by interaction with CGRP vascular receptors. Reported in vivo tests suggest that amylin is at least about 100 to 1000 times less potent than CGRP as a vasodilator (Brain et al., Eur. J. Pharmacol., 183:2221 (1990); Wang et al., FEBS Letts., 291:195-198 (1991)). Injected into the brain, amylin has been reported to suppress food intake (e.g., Chance et al., Brain Res., 539, 352-354 (1991)), an action shared with CGRP and calcitonin. The effective concentrations at the cells that mediate this action are not known. Amylin has also been reported to have effects both on isolated osteoclasts where it caused cell quiescence, and in vivo where it was reported to lower plasma calcium by up to 20% in rats, in rabbits, and in humans with Paget""s disease (see, e.g., Gilbey et al., J. Bone Mineral Res., S293 (1991). From the available data, amylin seems to be 10 to 30 times less potent than human calcitonin for these actions. Interestingly, it was reported that amylin appeared to increase osteoclast CAMP production but not to increase cytosolic Ca2+, while calcitonin does both (Alam et al., Biochem. Biophys. Res. Commun., 179(1):134-139 (1991)). It was suggested, though not established, that calcitonin may act via two receptor types and that amylin may interact with one of these.
Infusing amylin receptor antagonists may be used to alter glucoregulation. 8-37CGRP is a demonstrated amylin blocker in vitro and in vivo (Wang et al., Biochem. Biophys. Res. Commun., 181(3):1288-1293 (1991)), and was found to alter glucoregulation following an arginine infusion in fed rats (Young et al., Mol. Cell. Endocrinol., 84:R1-R5 (1992)). The initial increase in glucose concentration is attributed to arginine-stimulated glucagon secretion from islet alpha cells; the subsequent restoration of basal glucose is attributed to insulin action along with changes in other glucoregulatory hormones. When the action of amylin is blocked by preinfusion of 8-37hCGRP, the initial glucose increase is not significantly different, but there is a subsequent fall in glucose concentration to well below the basal level, which is restored only after some 80 minutes. Thus, glucoregulation following this challenge with an islet secretagogue was altered by infusion of an amylin receptor antagonist. Additionally, insulin concentrations were measured at half hour intervals and it was found that insulin concentration 30 minutes following the arginine infusion was almost twice as high in animals infused with an amylin receptor antagonist as in the normal controls. 8-37CGRP is also an effective CGRP antagonist. However, very similar results were seen with another amylin antagonist, AC66, which is selective for amylin receptors compared with CGRP receptors (Young et al., Mol. Cell. Endocrino., 84:R1-R5 (1992)). These results are said to support the conclusion that blockade of amylin action can exert important therapeutic benefits in Type 2 diabetes.
Patients with Type 1 diabetes, in addition to a lack of insulin, are reported to have marked amylin deficiency. As noted above, data show that amylin expression and secretion by pancreatic beta-cells is absent or well below normal in Type 1 diabetes. In several animal models of Type 1 diabetes, amylin secretion and gene expression are depressed (Cooper et al., Diabetes, 497-500 (1991); Ogawa et al., J. Clin. Invest., 85:973-976 (1990)). Measurements of plasma amylin in Type 1 diabetic patients show that amylin is deficient in these patients after an overnight fast, and that a glucose load does not elicit any increase in amylin levels (Koda et al., The Lancet, 339:1179-1180 (1992)).
It has also been discovered that, surprisingly in view of its previously described renal vasodilator and other properties, amylin markedly increases plasma renin activity in intact rats when given subcutaneously in a manner that avoids any disturbance of blood pressure. This is important because lowered blood pressure is a strong stimulus to renin release. Amylin antagonists, such as amylin receptor antagonists, including those selective for amylin receptors compared to CGRP and/or calcitonin receptors, can be used to block the amylin-evoked rise of plasma renin activity. These unexpected findings support the determination that amylin antagonists will reduce plasma renin activity with consequent therapeutic benefit in hypertension and cardiac failure and other disorders associated with elevated, inappropriate or undesired renin activity. Moreover, the additional ability of amylin antagonists to favorably modulate insulin resistance and other common metabolic disorders frequently associated with hypertension and cardiac disease provides a particularly desirable therapeutic profile.
Gastric hypomotility with delayed emptying of liquid and/or solid contents is a component of a number of gastrointestinal disorders. For a general discussion, see Goodman and Gilman""s The Pharmacological Basis of Therapeutics, Chapter 38 (Pergamon Press, Eighth Edition 1990). The symptoms of such disorders may include nausea, vomiting, heartburn, postprandial discomfort, and indigestion. Gastroesophageal reflux is often evident and can give rise to esophageal ulceration; there may also be respiratory symptoms or intense substernal pain that can be confused with asthma or myocardial infarction, respectively. Although the cause is unknown in the majority of patients, gastric stasis or hypomotility is frequently a consequence of diabetic neuropathy; this condition is also often present in patients with anorexia nervosa or achlorhydria or following gastric surgery. Id. at page 928.
The medical management of patients with gastric hypomotility usually includes the administration of a prokinetic agent. Although antiemetic phenothiazines or bethanechol may provide some relief, these drugs do not accelerate gastric emptying in the vast majority of patients and often produce unacceptable side effects. At present, available prokinetic agents include metoclopramide and cisapride, but others (e.g., domperidone) are being evaluated. Id.
Metoclopramide decreases receptive relaxation in the upper portion of the stomach and increases antral contractions. The pylorus and duodenum are relaxed, while the tone of the lower esophageal sphincter is enhanced. These effects combine to accelerate the emptying of gastric contents and to reduce reflux from the duodenum and the stomach into the esophagus. In addition, the transit time of material from the duodenum to the ileocecal valve is reduced as a result of increased jejunal peristalsis. Metoclophramide has little effect on gastric secretion or colonic motility. Id. at page 928.
In general, dopaminergic agonists produce the opposite pattern of effects, and these are mediated by D2 receptors that are located, at least in part, within the gastrointestinal tract. Id.
The mechanism of action of metoclopramide is poorly understood, even though it is clearly a dopaminergic antagonist and can block the gastrointestinal effects caused by the local or systemic administration of dopaminergic agonists. Although vagotomy does not abolish the effects of metoclopramide, its prokinetic actions can be blocked by atropine or other muscarinic antagonists. Moreover, not all dopaminergic antagonists speed gastric emptying. It is thought that the drug promotes the release of acetylcholine from myenteric neurons, although direct evidence of this action is lacking. Since bethanechol can enhance the effects of metoclopramide, enhanced responsiveness to acetylcholine may also be involved. Id. at pages 928-929.
Domperidone is a derivative of benzimidazole that possesses both prokinetic and antiemetic properties. It is a dopaminergic antagonist, and it produces marked hyperprolactinemia; its effects on gastrointestinal motility also closely resemble those of metoclopramide. However, unlike metoclopramide, these effects are not antagonized by atropine; and explanation for this difference has not yet been advanced. Domperidone crosses the blood-brain barrier to only a limited extent, and it causes extrapyramidal side effects only rarely. As a result, it does not interfere with the treatment of Parkinson""s disease, and it may be useful in counteracting the gastrointestinal disturbances caused by levodopa and bromocriptine. Thus far, the drug appears to have the same therapeutic utility as metoclopramide in the treatment of patients with gastric hypomotility. However, it has less antiemetic activity. Id. at page 929. Domperidone appears to be rapidly absorbed after oral administration, but its bioavailability is only about 15%; most of the drug and its metabolites are excreted in the feces. The half-time for its elimination from plasma is about 7 to 8 hours. Id. Domperidone is not generally available in the United States; it is available elsewhere as MOTILIUM. Optimal dosage has not been established, but daily oral doses of 40 to 120 mg have been utilized in the treatment of gastric hypomotility. Id. at page 929.
Cisapride is a benzamide and its effects on the motility of the stomach and small bowel closely resemble those of metoclopramide and domperidone; however, unlike these drugs, it also increases colonic motility and can cause diarrhea. The mechanism of its gastrointestinal actions is poorly understood. Like metoclopramide, these actions are blocked by atropine and may involve the release of myenteric acetylcholine. Cisapride appears to be devoid of dopaminergic blocking activity, and it does not influence the concentration of prolactin in plasma or cause extrapyramidal symptoms. The drug binds to and blocks 5xe2x80x94HT2 tryptaminergic receptors in the rat ileum, but the relationship of this action to its effects in man has not been established. Id. Thus far the efficacy of the drug in the treatment of disorders of gastric hypomotility appears to equal those of metoclopramide and domperidone without the side effects that result from dopaminergic blockage. In additional, cisapride may be useful in the treatment of patients with chronic idiopathic constipation or with colonic hypomotility due to spinal cord injury. Id. at page 929.
In contrast to the above, agents which serve to delay gastric emptying have found a place in medicine as well, particularly as diagnostic aids in gastro-intestinal radiologic examinations. For example, glucagon is a polypeptide hormone which is produced by the alpha cells of the pancreatic islets of Langerhans. It is a hyperglycaemic agent which mobilizes glucose by activating hepatic glycogenolysis. It can to a lesser extent stimulate the secretion of pancreatic insulin. Glucagon is administered as glucagon hydrochloride; doses are usually expressed as glucagon.
Glucagon is used in the treatment of insulin-induced hypoglycaemia when administration of glucose intravenously is not possible. It is given by subcutaneous, intramuscular, or intravenous injection in a dose of 0.5 to 1 mg (unit), repeated if necessary after 20 minutes. However, as glucagon reduces the motility of the gastro-intestinal tract it is used as a diagnostic aid in gastro-intestinal radiological examinations. The route of administration is dependent upon the diagnostic procedure. A dose of 1 to 2 mgs (units) administered intramuscularly has an onset of action of 4 to 14 minutes and a duration of effect of 10 to 40 minutes; 0.2 to 2 mgs (units) given intravenously produces an effect within one minute that lasts for 9 to 25 minutes.
Glucagon has been used in several studies to treat various painful gastrointestinal disorders associated with spasm. Daniel et al. (Br. Med. J., 1974, 3, 720) reported quicker symptomatic relief of acute diverticulitis in patients treated with glucagon compared with those who had been treated with analgesics or antispasmodics. A review by Glauser et al., (J. Am. Coll. Emergency Physns, 1979, 8, 228) described relief of acute oesophageal food obstruction following gulcagon therapy. In another study glucagon significantly relieved pain and tenderness in 21 patients with biliary tract disease compared with 22 patients treated with placebo (M. J. Stower et al., Br. J. Surg., 1982, 69, 591-2). Franken et al., however, (Radiology, 1983, 146, 687) failed to show any advantage of glucagon over placebo in the hydrostatic reduction of ileocolic intussusception in a study of 30 children, and Webb et al. (Med. J. Aust., 1986, 144, 124) concluded that glucagon was ineffective in the management of ureteric colic in a casualty department.
We have now discovered that, surprisingly in view of its previously described hyperglycemic properties, amylin and amylin agonists, including as those described herein, for example, the amylin agonist analogue 25,28,29Pro-h-amylin [SEQ ID NO:1] (also referred to as xe2x80x9cAC-0137xe2x80x9d), can reduce gastric motility and slow gastric emptying, as evidenced by the ability of such compounds to reduce post-prandial plasma glucose levels.
The present invention is directed to novel methods for reducing gastric motility and slowing gastric emptying, comprising the administration of an amylin or an amylin agonist, for example, the amylin agonist analogue AC-0137. These methods will be useful in the treatment of, for example, post-prandial hyperglycemia, a complication associated with type 2 (non-insulin dependent) diabetes mellitus.
The term xe2x80x9camylinxe2x80x9d is understood to include compounds such as those defined by Young and Cooper in U.S. Pat. No. 5,234,906, issued Aug. 10, 1993, for xe2x80x9cHyperglycemic Compositions,xe2x80x9d the contents of which is hereby incorporated by reference. For example, it includes the human peptide hormone, and species variations of it, referred to as amylin and secreted from the beta cells of the pancreas. xe2x80x9cAmylin agonistsxe2x80x9d is also a term known in the art, and refers to compounds which mimic the effects of amylin. Thus, amylin itself and amylin agonist analogues may also be referred to broadly as amylin agonists. The term xe2x80x9camylin agonist analoguexe2x80x9d is understood to refer to derivatives of an amylin which act as amylin agonists, normally, it is presently believed, by virtue of binding to or otherwise directly or indirectly interacting with an amylin receptor or other receptor or receptors with which amylin itself may interact to elicit those biological properties referred to above. In addition to those described herein, other useful amylin agonist analogs are identified in an International Application, WPI Acc. No. 93-182488/22, entitled xe2x80x9cNew Amylin Agonist Peptides Used for Treatment and Prevention of Hypoglycemia and Diabetes Mellitus,xe2x80x9d the contents of which is also hereby incorporated by reference.
In a first aspect, the invention features a method of beneficially regulating gastrointestinal motility in a subject by administering to said subject a therapeutically effective amount of an amylin or an amylin agonist, preferably an amylin agonist analogue. In one embodiment, the methods of the present invention are directed to reducing gastric motility. In another embodiment, the invention is directed to methods of delaying gastric emptying.
These methods may be used on a subject undergoing a gastrointestinal diagnostic procedure, for example radiological examination or magnetic resonance imaging. Alternatively, these methods may be used to reduce gastric motility in a subject suffering from a gastrointestinal disorder, for example, spasm (which may be associated with acute diverticulitis, a disorder of the biliary tract or a disorder of the Sphincter of Oddi).
In another aspect, the invention is directed to a method of treating post-prandial dumping syndrome in a subject by administering to the subject a therapeutically effective amount of an amylin agonist.
In yet another aspect, the invention is directed to a method of treating post-prandial hyperglycemia by administering to a subject a therapeutically effective amount of an amylin agonist. In a preferred embodiment, the post-prandial hyperglycemia is a consequence of Type 2 diabetes mellitus.
Preferred amylin agonists include 25,28,29Pro-h-amylin. Preferred amylin agonist analogues also include 25,28,29Pro-h-amylin.
In another aspect, the present invention is directed to a method of treating gastric hypomotility in a subject by administering to the subject a therapeutically effective amount of an amylin antagonist. In preferred embodiments, these methods may be employed where hypomotility is a consequence of diabetic neuropathy or where hypomotility is a consequence of anorexia nervosa. Hypomotility may also occur as a consequence of achlorhydria or as a consequence of gastric surgery.
In another aspect, the invention is directed to a method of accelerating gastric emptying in a subject by administering to the subject a therapeutically effective amount of an amylin antagonist. By amylin antagonist is meant a compound which interferes with the effects of amylin, for example, a compound that is itself lacks significant pharmacological activity but causes effects by inhibition of action of a specific agonist e.g., by competition for agonist binding sites. Preferably, the amylin antagonist used in these methods is an amylin receptor antagonist. A preferred antagonist is acetyl-11,18Arg, 30Asn, 32Tyr9-32calcitonin (salmon) [SEQ ID NO:2].
In another aspect, the invention is directed to a method of treating ingestion of a toxin by administering an amount of an amylin or an amylin agonist effective to prevent or reduce passage of stomach contents to the intestines and aspirating the stomach contents.